Nearly________ of the surface of our planet is covered by water.
The three sisters decided to hold a family party to _______their parents’ silver wedding .
Usually John would be late for meetings .But this time ,________to my surprise ,he arrived on time .
There have been several new events ______to the program for the Beijing Olympic Games .
Wang Wei had served ______a volunteer for three years before he graduated from college .
The little boy ,out of curiosity ,_______the toy to see how it worked ,but couldn’t put it together .